(111) Prevalence of Polypharmacy, Multimorbidity and Association with Mortality in Older Aboriginal and Torres Strait Islander People.

Background: Aboriginal and Torres Strait Islander people account for 3.8% of Australia’s population. Despite continued health and social inequities across the lifespan, the proportion aged ≥50 years has almost doubled from 9.9% in 2001 to 17.6% in 2021. However, as a consequence of these inequities, older Aboriginal and Torres Strait Islander people have early onset of chronic health conditions, together with increased prevalence and mortality compared to the non-Indigenous population.

Objectives: The aim of this study was to examine the national prevalence of multimorbidity and polypharmacy, and association with mortality in older Aboriginal and Torres Strait Islander people.

Methods: A retrospective cohort study of Aboriginal and Torres Strait Islander people aged  50 years entering aged care between 1 January 2017 and 31 Dec 2018 was conducted using data from the Registry of Senior Australians, a linked population-based aged care and health data platform. Prevalence of polypharmacy (>=5 medicines), hyperpolypharmacy (>=10 medicines) and multimorbidity (>=2 chronic conditions identified using Rx-Risk comorbidity index and aged care health assessment data) and 95% confidence intervals (CI) were calculated. Cox proportional hazards models adjusted for age, sex, and social disadvantage were used to examine association between multimorbidity and mortality.

Results: A total of 4036 Aboriginal and Torres Strait Islander individuals were included with a median age 67 years (IQR 59-75), 58% were female, median of 6 (IQR 4-8) chronic conditions and 10 medications (Interquartile range (IQR) 6-14). The prevalence of polypharmacy was 86% (95% CI 84-87), hyperpolypharmacy 54% (95% CI 52-55) and multimorbidity was 95% (95% CI 94-96). Five percent of individuals had 0-1 health conditions, 25% had 2-4 conditions, 28% 5-6 conditions, 24% had 7-8 and 18% had >=9 conditions. Within 12 months from study entry 14.3% (95% CI 12.3-15.4) died. Increasing multimorbidity was associated with higher risk of mortality (2-4 conditions Hazard Ratio (HR) 1.3 95% CI 0.9-1.9; 5-6 conditions HR=1.5 95% CI 1.0-2.3; 7-8 conditions HR=1.9 95% CI 1.3-2.7; 9 conditions HR=2.3 95% CI 1.5-3.4).

Conclusions: This study highlights the high prevalence of polypharmacy and multimorbidity in older Aboriginal and Torres Strait Islander people, and the association between multimorbidity and higher risk of mortality. Consideration of social, cultural and spiritual wellbeing, to reduce disparities, improve access and development of community informed culturally appropriate aged and health care services is urgently needed to achieve optimal health and wellbeing.